


Our Sin

by Anonymous



Category: Little Busters!
Genre: F/M, Incest, Smut
Language: English
Status: Completed
Published: 2020-02-17
Updated: 2020-02-17
Packaged: 2021-02-27 13:00:11
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 2,543
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22377592
Author URL: https://archiveofourown.org/
Summary: When Rin comes to Kyousuke for a heart to heart, events take an unexpected turn.
Relationships: Natsume Kyousuke/Natsume Rin
Kudos: 5
Collections: Anonymous





	Our Sin

Kyousuke was so absorbed in his manga that he didn't hear the door open.

"Hey." The soft voice pulled him away and he looked up. Rin was standing there with an uncertain expression, her brow furrowed.

"Oh, Rin. What's up?" Kyousuke set aside the manga. "You want something?"

"Mmm." Rin's eyes slid sideways and she shuffled her feet slightly. "I don't know. I was wondering if you wanted to, like, talk or something, maybe?"

This was certainly unusual. Rin was coming to him to talk? They used to talk together all the time when they were younger, but as the years went by and they grew older, they hadn't done it so much and now Rin had a whole bunch of new friends to spend time with. Why wasn't she with one of the girls, he wondered. Still, he was hardly going to complain if his dear little sister wanted to spend time with him for a change. Honestly, Kyousuke did miss it somewhat, even if he was glad to see Rin make new friends. 

"Well, alright." Kyousuke went over to sit on the bed and Rin sat next to him. "Is there anything in particular that you want to talk about? Your dear older brother is very happy to listen."

Rin stayed silent, staring at her feet. This really wasn't like her. Something had to be bothering her.

"You didn't want to go and be with the girls? You haven't had a falling out or anything like that, right?"

The ring of a bell sounded out as Rin shook her head in response. "It's nothing like that. I really do like being with them. But..." She trailed off.

"But?"

"Mmm." Rin sighed, lifting her head. "It's going to sound kinda dumb but I guess I just feel a little lonely. That's weird, isn't it? Why would I feel lonely, I have everyone around me, but... I just don't know."

"That doesn't sound too weird." Kyousuke placed a hand on her head. Maybe the fact Riki was dating one of the girls was also troubling her, he supposed, but her time would come soon enough. Once again they would pursue the secret of the world and fall in love with each other. . That was the future he envisioned for them both. "We're all growing up, you know. Things change."

"Yeah." Rin folded her arms, her head drooping. "But sometimes I wish it didn't have to. I wish everything could stay the same forever." 

"So do I." Kyousuke felt a pang. One day, he was going to have to say goodbye to Riki and Rin. How he wished he could stay with them forever, but it wasn't to be. He was startled out of his thoughts by Rin leaning against him. She sure was feeling unusually affectionate this evening. Were things really that bad? Kyousuke slipped an arm around her, half expecting her to draw back and respond with some annoyed retort, but she just burrowed into him even more.

"We don't really talk much like we used to, huh."

"No, I guess not. Your big brother just isn't cool enough for you anymore. Ahh. I remember the days when you used to hug me and call me Onii-chan."

"What are you talking about? I never called you that!" Rin responded in a voice laced with irritation. Oh good, she was still acting somewhat like herself after all. He was almost afraid she had been switched with a body double.

"Why don't you want to?"

"Because it's kinda embarrassing. Anyway, Kyousuke is Kyousuke, so there."

"Alright then. Having you call me Onii-chan would be kind of weird anyway." 

Rin twisted herself around, her luminous red eyes meeting his. "You won't ever leave me alone, right? Even if you are an idiot, I wouldn't ever want you gone because that would be really sad. I don't want you to go anywhere."

Kyousuke swallowed, feeling a lump form in his throat, and he averted his gaze. "I'll be with you for as long as I can, Rin."

"Huh?" Rin's brow furrowed. "Wait, what does that mean?"

"Nothing," Kyousuke said quickly, flashing her a reassuring smile. He started stroking her head. "You know, I'm going to have to get a job eventually and you've got the rest of school and college, and then you'll be getting a job too... you know, we're going to become adults someday."

Rin didn't seem appeased by his hasty excuses. "Do you not want me around you anymore? Don't you like me?"

Kyousuke let out a short laugh. "Come on, what kind of question is that? Of course I do. You are my dear little sister and I love you."

"You do?" Rin bowed her head, peeking through her bangs. A light flush crept through her cheeks.

"Yeah." Kyousuke rubbed her head again. "Of course I do."

"Mmm." Rin lowered her head even further, hiding her eyes. "Then..."

"Hm?"

A long moment of silence followed in which Rin seemed to be thinking about something. Kyousuke quietly waited, wondering just what in the world was going through her mind right now. Before he knew what was happening, she had slid onto his lap and pressed her lips to his. His mind went blank and he stiffened. She was kissing him. After a few seconds, he lightly pushed her away, spluttering.

"Rin? Just what do you think you're doing?"

"I kissed you." Rin's cheeks were red. She looked down, fidgeting. "I thought I should try it. Didn't you like it?"

"What?" Kyousuke shook his head. "But, why would you do such a thing? You're my sister. Kissing me on the lips is a bit weird, isn't it?"

Rin looked up again, her eyes flashing with confusion. "But I thought you liked me. You said you loved me."

"I didn't mean like that!"

"Oh..." Rin's voice wobbled. Her shoulders sank. "But... but... I... I just wanted to..."

"Rin." Kyousuke exhaled, pressing a hand to his forehead. This couldn't be happening. He couldn't believe it. Rin had just come on to him. His own little sister. This was wrong. Something had gone seriously wrong. "I don't understand. Do you really like me? Like, you know?"

"I... well..." Rin's cheeks reddened further. "I was thinking, maybe, you're not that bad after all. Like, you're kinda cool, maybe, and, well, I really wanted to kiss you all of a sudden. Was it wrong?"

Kyousuke lowered his hand, gazing at her. This was Rin. His cute, innocent little sister. Could he really? "We're brother and sister," he protested, his voice weak. "We can't do this."

"Well, why don't we just pretend?" Rin moved in closer, Her hand brushed against his groin and he stiffened even further, letting out a soft gasp. "Hm?" She looked down. "Hey, does it feel good if I touch you there?"

Kyousuke drew in a sharp breath as Rin started rubbing her hand against his groin. "Rin," he gasped out. He should be pushing her away, so why wasn't he? He ground his teeth, becoming painfully aware of the tingles of arousal coursing through him. Damn, why did it feel so good?

Rin looked up, watching her brother's face as she continued rubbing his genitals. He had his eyes screwed shut. "You like it, don't you?"

Kyousuke started to writhe, letting out a loud gasp. Yes, it did feel good. It made him want even more. A voice in his head was screaming at him that it was wrong, that he should stop, but the more aroused he was feeling, the less he cared.

Anyway, this was a dream world. At the end of this loop, Rin's memories would be erased, wouldn't they? That way, they could do this with no consequences. He could do whatever he wanted, couldn't he? Even if it meant crossing into a forbidden territory.

Kyousuke opened his eyes, meeting Rin's gaze. "I do."

"Then kiss me."

Kyousuke licked his dry lips and swallowed, taking hold of Rin's arms and moving in for a kiss. He pressed his lips to hers firmly. A thrill ran through his body as their lips touched. He savoured the feel of her soft lips rubbing against his. They pulled apart after a few seconds and Rin sighed with a dreamy smile.

"That felt so good."

"Rin." Kyousuke regarded her with a serious look. "Do you want to go further?"

"You mean, like, do it?" Rin's eyes widened.

"We don't have to if you don't want to."

Rin lowered her gaze, her brow furrowing, then she looked back at him with determined eyes and nodded. "Yeah. I want to."

Kyousuke gazed at her without saying anything for a while, his heart pounding all the while. Could he really do this? Even as he tried to reason with himself, another part of him was urging him on. The world would reset and it would be as if nothing had happened. What was there to lose? He didn't have to worry about Rin's innocence or how this would affect her. Everything would be fine, wouldn't it? Just this once couldn't hurt. He gently disentangled himself from her and went to lock the door. 

Rin clambered onto the bed and sat, legs spread out, waiting. Kyousuke came back and crawled onto the bed, kissing her again. He enfolded her in his arms as he kissed her deeply. Rin pressed back, clutching him in a fierce embrace. A soft moan rumbled in her throat. Kyousuke pulled back, breathing heavily as he looked into his little sister's eyes. He then started to disrobe her, pulling away her jacket and vest before undoing the buttons of her shirt, exposing her bare body with pert breasts tucked away behind a sports bra. Rin started doing the same, pulling his clothes away to reveal his bare chest.

Kyousuke cupped her waist, running his hands along her soft warm flesh up to her breasts and around the back to undo the clasps. He then brought his hands to her breasts, running them over the fleshy mounds and gently teasing her peaked nipples with his thumbs. With a gentle motion, he pushed Rin down onto the bed and took one of her nipples into his mouth, running his tongue around the pointed tip. Rin wriggled under him, a pleasured sigh passing through her lips. Kyousuke's hands gently squeezed and massaged her breasts as he continued teasing her nipples with his tongue. He then moved his lips up her body until they reached her collarbone and he nuzzled her neck. Rin writhed slightly with a murmur. Kyousuke kissed her again, relishing the touch of her soft, warm lips as he held onto her body. 

"Are you ready?" Kyousuke whispered.

"Of course I am."

"Just making sure." Kyousuke pushed down his undergarments, revealing his already hardening cock. He brought his hands to Rin's hips, gently gripping them as he slid forward, bringing the tip of his erection toward her moist cave. Kyousuke took a deep breath. There was no turning back from this now. While slowly releasing his breath, he slid inside of her, feeling her moist walls close around his cock.

Rin gasped. "Ahh." Her fingers curled around the sheets. She moaned again as Kyousuke began to slide back and forth with careful, gentle motions.

Kyousuke watched her writhe about under him, making impassioned sounds, while he continued to thrust, taking it slowly at first. Seeing how much she was enjoying it, his confidence gradually grew and he picked up the pace, making harder and faster thrusts. Rin's motions became even more frenzied and her cries increased in volume. Kyousuke lay down on top of her, kissing her and muffling her sounds of arousals, thrusting fervently. It felt so good inside of her, feeling her warm, moist walls rubbing against his cock. He didn't even care how wrong it was anymore, he was just enjoying the moment. This was his first time and it felt amazing, regardless of who it was even with.

"Mmm... ahh..." Rin wrapped her arms around Kyousuke, raking her nails against his skin. She arched her body upwards, throwing her head back. Kyousuke embraced her in turn, kissing her neck and nuzzling the soft skin while thrusting inside of her. He glanced at her face, seeing a look of sheer rapture. Rin met his gaze with a bright smile. "Don't stop. Keep going."

Kyousuke leaned in for another kiss, keeping up the pace and humping her furiously. She didn't complain even once, continuing to make various noises out of sheer pleasure. His cock was swelling, ready to unleash its load at any second. Kyousuke clutched Rin tighter and cried out as he released his seed, firing it inside of his little sister. When it was all spent, he went limp, collapsing on top of her and panting heavily. Rin's arms flopped to her sides and she stared upward with dazed eyes, chest heaving with every breath she took.

"That was amazing," Rin whispered. Her damp bangs clung to her forehead and her skin shimmered with sweat. She reached up with a hand, running it through Kyousuke's hair. Kyousuke raised his head, gazing at her flushed, smiling face, and he brought a hand to her cheek, gently stroking it.

"Yeah," Kyousuke murmured. He gazed at her for a little while longer with a warm smile, before rolling off her and flopping onto his back. Her hand found his and they curled their fingers together. "I still can't believe we did that."

"Hm, yeah. I suppose everyone else would be surprised too, wouldn't they?"

Kyousuke turned his head, glancing at her. "We can't tell them, Rin." Even if memories could be reset, it was too dangerous. It was better this remained between the two of them for now, until the reset came. Then it would be his sinful secret alone. Rin wouldn't remember any of it. 

"Oh, we can't? Okay then." Rin rolled over onto her side. "But we can do this again, right?"

Kyousuke turned over to face her and reached out to stroke her hair without saying anything. He supposed they could, for as long as this timeline continued. Once Riki was able to solve the troubles that would face him, it would end and the world would be reset. Rin would forget about everything they had done. Would she come to him again? He didn't know, and he wasn't sure what he would do in that situation.

It had felt so good, doing it with her, even if he knew what a sin it was to do so. Of course, it wasn't like they could be together. Riki and Rin being with each other was the true endgame. They would spend the rest of their lives together in the future where everyone else was gone. He was sure of that. 

Still, while they were still in this dream, surely he could do as he wished? Rin's memories could be reset. She was bound to develop feelings for Riki again. Surely his actions couldn't have consequences. It would be fine. If she came to him again, why not?

Rin was watching him with a concerned look, waiting for him to speak.

Kyousuke kissed her forehead and smiled at her. "Of course we can."


End file.
